The Conservative party has been at the centre of an election expenses scandal for over a year. The situation has now boiled over, with the party being fined £70,000 for misreporting spending in 2014 – the largest amount a British political party has ever had to pay.

The key allegations in this case are that in three 2014 by-elections, the Conservatives omitted campaign costs from spending returns. They also stand accused of failing to correctly report general election campaign costs. A key question is whether so-called “battlebus” expenses – spending to shuttle campaigners into constituencies – were incorrectly reported by the party as national, not local, spend.

The fine follows an investigation by the Electoral Commission, which found that expense returns related to the three parliamentary by-elections in 2014 “understated the value of the Party’s spending on their campaigns”. It also says the 2015 general election spending return “was not a complete statement of its campaign spending payments” and that payments were included “that were not party campaign spending” and that “omitted other party campaign payments”.

All in all, the party’s 2015 general election spending return was missing at least £104,765 in payments. The Commission also found that £118,124 in payments was either not reported, or incorrectly reported to the Commission. Finally, it found that the party did not include invoices or receipts for payments to the value of £52,924. That’s £275,813, at least, that is unaccounted for.

Behind the jargon this means that in 2015, the Electoral Commission believe that some local spending was misfiled as national spending. This is likely to relate to spending on the buses.

What is national and local spend?

There are two types of spending in British elections – local and national. Each has a different limit. Limits on local spending (to promote a particular constituency candidate) are not uniform, but are often around £15,000. The limit on national spending (to promote the party more generally) is £19.5m, which is very rarely close to being reached. In 2015, the Conservatives came closest, spending £15.6m.

What now?

It has also been reported that 12 police forces passed files to the Crown Prosecution Service alleging that up to 20 Conservative MPs broke the aforementioned spending rules.

If the CPS finds evidence of wrongdoing, the best the Conservative party can hope for are further fines being levelled to the national party. In some cases, it’s possible that elections will end up being re-run – creating a raft of potentially awkward by-elections for the party. Former UKIP leader Nigel Farage has already stated an interest in standing again in Thanet South (presuming he’s not too busy in the US) if this is the case (eighth time’s a charm).

Farage fails to win Thanet South in 2015.PA

Finally, there is the possibility of jail time – though this remains somewhat improbable, and it is unwise to speculate around ongoing police investigations.

However, this would be an exceptional circumstance. As The Guardian has outlined, a recent analogue to this case was Fiona Jones, Labour MP for Newark, who was found guilty of fraud in 1999 – although her case was overturned on appeal. Those wishing to find out more about this subject might want to take a deep dive into the so-called “In and Out Scandal” in Canada.

Is it only the Conservatives?

It’s worth repeating that this episode may (or should) change the way elections are run. British journalist Stephen Bush has suggested that election spend could become like the expenses scandal – something that started as a Labour story but became systemic. Indeed, the Electoral Commission seems to state as much:

This is the third investigation we have recently concluded where the largest political parties have failed to report up to six-figure sums following major elections, and have been fined as a result. There is a risk that some political parties might come to view the payment of these fines as a cost of doing business.

Beyond partisan point scoring, there is truly a case to uncover whether the disregard for reporting national and local spend is merely the done thing in the heat of a campaign. And if so, whether these rules are fit for purpose.

The episode will continue to run and run for the Conservatives, potentially leading to some awkward by-elections, and possibly further fines. What will be truly interesting to see is whether the Conservatives face scrutiny regarding these allegations. Last year, only the SNP’s Angus Robertson asked questions in parliament. Although Labour’s deputy leader, Tom Watson, has been tweeting about the Conservative scandal, sometimes in politics, the really telling things occur in the silence.